1. Field of the Invention
The invention relates in general to a display device, and more particularly to a lower power display device.
2. Description of the Related Art
A display panel of a liquid crystal display (LCD) device comprises a plurality of scan lines and a plurality of data lines across each other to form an active area. A pixel electrode and thin film transistors are formed in the active area. A scan driver and a data driver respectively provide scan signals and data signals to the scan lines and the data lines.
FIG. 1A shows a block diagram of the LCD 10 with a plurality of pixels 11 arranged on intersection of data lines 13 and scan lines 14, forming an array 12. Each data line 13 is coupled with the data driver 15 to transfer display image data from the data driver 15 to be input to pixels 11 arranged on the scan line 14 by synchronously scanning a scan driver 16.
FIG. 1B shows a pixel structure of the pixel 11 and FIG. 1C shows a cross-section of the cutting line indicated I-J of FIG. 1B. The common electrode 20 is perpendicularly arranged on the data line 13. The common electrode 20 and the data line 13 form a parasitic capacitor 21.
The product of resistance R and capacitor C is related to a time constant RC of a signal transmitted by the data line 13. This becomes a more critical issue in a display industry, especially for a higher resolution display, because the time constant RC is associated with the delay time. In order to improve the problem of the delay time caused by RC delay effect, either the resistance R or the capacitor C should be reduced.
In one aspect, the display image data transferred along with data line 13 has high frequency corresponding to the display resolution (row number) and frame frequency. The charging and discharging of the parasitic capacitor 21 induces energy consumption in the data driver. Namely this panel consumes power proportional to the frame frequency. It is in fact that this power consumption is a great part of panel power consumption. Therefore, rescuing the parasitic capacitor 21 results in reducing panel power consumption.
Another aspect of reducing the parasitic capacitor is to reducing the time constant RC associated with resistance R. Low RC on the data line 13 makes faster charge and discharge which is necessary for high resolution display. Display used in a mobile electronics such as mobile phone, low power consumption is one of the most essential feature so as to extend the battery life whilst the display goes to higher resolution.